A METHOD AND AN APPARATUS FOR SPREADING WARHEADS

Abstract: The present invention relates to a method and an apparatus for transforming a warhead (4) from a first state in which it constitutes a part of a capsule (1) flying in an aerodynamic trajectory, to a second state in which the warhead (4) follows its own ballistic ejection trajectory with more or less the same main direction but at substantially higher altitude above ground level. The invention also includes the employment of a rocket motor (5) for changing the flight path and how this is united to the warhead (4).

Description: TITLE OF INVENTION: A method and an apparatus for spreading warheads TECHNICAL FIELD The present invention relates to a method and an apparatus for transforming a warhead from a first state under which it forms a part of a larger unit for capsule flying in an aerodynamic trajectory such as, for example, a cruise missile, into a second state under which it follows its own ballistic ejection trajectory with more or less the same major direction but at a substantially higher maximum flight altitude. Such modification of the flight path as entails a change from having been a part of a larger unit which follow one aerodynamic trajectory into following its own ballistic ejection trajectory may be desirable when it is a matter of spreading, from a capsule, a large number of warheads so that these together cover a predetermined surface area at ground level. Warheads relevant in this context could be, for example, mines, impact- detonated so-called subcombat units of the hollow charge type or more sophisticated constructions such as combat units of a general type which are described in European patent application No. 0252036. This latter warhead type is provided with its own target seeker which, while warheads fall towards the ground under retarded fall, scan ground level for combat- worthy targets against which the target seeker discharges, in such an event, the effective charge of the warhead. The warhead type is in fact generally conveyed to the target area by an artillery shell from which it is ejected at a position adapted in relation to the target, but it could also be conveyed to the proximity of the target area by a capsule in the form of a cruise missile provided with its own target seeker which itself determines when it is to eject a number of warheads which then, in predetermined ejection trajectories, are spread over the assumed position of the target in order there, during the downwardly directed sections of each respective ejection trajectory, to scan ground level for combat- worthy targets. A warhead which is separated from a capsule flying at high speed in an aerodynamic trajectory will have its own flight path which will be dependent upon the flight speed of the capsule in relation to the warhead's own ejection velocity and ejection angle. Correctly adapted to one another, these can impart to the warhead a forwardly directed ejection trajectory with desired maximum altitude and ejection length. In order that the ejection length will not be too long, it may be appropriate to make the ejection operation fire obliquely rearwardly. If the capsule moves at high velocity (as is presupposed here) , a relatively high ejection velocity will be required, which entails demands for a rocket motor whose size is not negligible in relation to the warhead. It may be assumed that the capsule which, thus, must initially contain a plurality of warheads, cannot be made so stable that an ejection system of the gun type could be usable. Since the ejection rocket motor will have a certain size in relation to the warhead, it must be removed from the warhead as soon as it is no longer needed, i.e. as soon as it has burnt out. Otherwise, it will influence the ejection trajectory of the warhead, which is not desirable. The object of the present invention is to devise an extremely simple solution to this problem. The invention, which has otherwise been defined in the appended claims, is thus based on the concept that the communication between the warhead and the rocket motor is such that the aerodynamic forces and inertia forces acting on these units break down this connection as soon as the rocket motor has burnt out and no longer acts on the warhead in the flight direction. This fundamental principle (which is illustrated in the accompanying drawings) may thus consist of a loose lap joint in the form of concentric ring edges of relatively low height disposed inside one anothe . The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 shows a fundamental concept for the employment of warheads of the type contemplated here; Fig. 2 shows the variables determinative of the launching process; Fig. 3 shows, partly in cross section, a warhead and its rocket motor; and Fig. 4 shows the same details as in Fig. 3, but once the separation between the parts has been commenced. DESCRIPTION OF PREFERRED EMBODIMENT The capsule 1 illustrated in Fig. l is on its in-flight path towards the target 2. When the target seeker of the capsule has identified the target 2, the capsule begins to eject complete warhead 3. These consist of actual warheads 4 and rocket motors 5. On the figure, the ballistic ejection trajectories 6-9 are intimated for 4 warheads ejected in sequence after one another. The trajectories of the rocket motors have been marked 6a-9a in a corresponding manner. If the ejection is made progressively during flight, there will be obtained, as is apparent from the figure, an elongate blanket cover at ground level. Lateral cover is realized by the. ejection tubes 10 of the capsule being given slightly different lateral directions. The different variables determinative of the ejection trajectory of the capsule are intimated in Fig. 4. The complete warhead 3 shown on a larger scale in Figs. 3 and 4 thus consists of the actual warhead 4, whose details are of no significance here and will, therefore, not be considered, as well as the rocket motor 5. This latter is of the high efficiency type, but with a very short burn time. The trajectory which is illustrated in the figure has, for example, seven outlet nozzles 11. The connection between the warhead 4 and the rocket motor 5 consists, as is apparent from the figure, solely of a low cylindrical outer edge 12 to the warhead 4 which surrounds and lies concentrically outside a corresponding annular edge 13 in the edge of the rocket motor 5 facing towards the warhead. As long as these parts are located in the capsule, they are held together by the adapted ejection tube 10, while, as soon as the rocket motor 5 has been started, there kept together by the compression acceleration with which the motor acts on the warhead 4. When the burn time of the rocket motor is completed (which takes place when the complete warhead is located a few metres above the capsule) , the aerodynamic forces will, through their angle of attack against * the warhead 4 and the rocket motor 5, respectively, break apart these sections which will thereafter follow their own trajectories. The angle of attack of the aerodynamic forces is determined by the ejection angle α which, in turn, is adapted to the flight speed of the capsule and the ejection velocity of the complete warhead 3. By adaptation of these variables to one another, the warhead proper can thus be given a suitable ejection trajectory towards the target 2 indicated by the target seeker of the capsule 1. The aerodynamic forces attack the rocket motor 5 and warhead 4, respectively, in such a manner that momentary forces occur with the centre of rotation in the plane division between the rocket motor and the warhead so that a division process according to Fig. 4 is started. After the division, the rocket motor and warhead, respectively, will each have their different ballistic trajectories in that they are of different masses and possess different coefficients of resistance. In order to hasten the separation of these two, a resilient packing or the like could be applied in the space 14 between the rocket motor 5 and the warhead 4. The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the spirit and scope of the appended claims.

Claims: WHAT WE CLAIM AND DESIRE TO SECURE BY LETTERS PATENT IS. A method of transforming a warhead (4) from a first state in which it constitutes a part of a capsule (1) flying in an aerodynamic trajectory, to a second state in which the warhead (4) follows its own ballistic ejection trajectory (6) with more or less the same main direction but at substantially higher altitude above ground level, chazacterized in that the warhead (4) is ejected out of the capsule (1) by means of a rocket motor (5) connected therewith, in a direction obliquely rearwardly and upwardly in the flight direction of the capsule (l) , and the connection between the warhead (4) and the rocket motor (5) being such that the aerodynamic forces acting on the warhead and the rocket motor break apart these two after the rocket motor has burnt out, whereafter the parts follow their own different ejection trajectories. 2. The method as claimed in Claim 1, chazacterized in that the connection between warhead (4) and rocket motor (5) has been given the form of a loose lap joint (12-13) in which the area of the joint determines how soon after the burnout of the motor (5) the parts are to be broken apart. 3. The method as claimed in Claim 2, chazacterized in that the warhead (4) and rocket motor (5) are held together up to motor ignition in that they are housed together in an ejection tube (10) from which they are permitted to move only after the motor (5) has been started. 4. The method as claimed in any one or more of Claims 1-3, chazactezized in that the ejection direction of the warhead (4) out of the capsule (l) is not more rearwardly directed in the flight direction of the capsule than the resulting velocity between the flight speed of the capsule and the ejection velocity of the rocket motor 5 gives a forwardly directed trajectory tangent (6) . 5. An apparatus, in accordance with the method as claimed in any one or more of Claims 1-4, for transforming a warhead (4) from a first state in which it constitutes a part of a capsule (1) flying in an aerodynamic trajectory, to a second state in which the warhead (4) follows its own ballistic ejection trajectory (6) with more or less the same main direction but at substantially greater altitude above ground level, chazactezized in that it partly includes an obliquely rearwardly disposed ejection tube (10) seen in the flight direction of the capsule, and partly a warhead (4) disposed in the ejection tube, and partly a rocket motor (5) releasably connected to the warhead. 6. The apparatus as claimed in Claim 5, chazactezized in that the interconnection between the warhead (4) and the rocket motor (5) consists of an overlap between the two parts which is dimensioned such that the division process is not prevented. 7. The apparatus as claimed in Claim 6, chazactezized in that a resilient washer which is held compressed in the ejection tube and is, as long as the rocket motor (5) burns, disposed between the motor and the warhead (4) and which, on burnout of the rocket motor when the acceleration ceases, imparts an extra impulse to the division process between the rocket motor and the warhead.

Inventors: AXINGER JAN, HOLM ANDERS, AXINGER, JAN, HOLM, ANDERS
Applicants: AXINGER JAN, BOFORS AB, HOLM ANDERS, AXINGER, JAN, HOLM, ANDERS
Application year: 1994
Main classification: F42B12
IPC codes: F42B12, F42B15